ADA4051-2_VB Datasheet, PDF (1/5 Pages) Analog Devices – Low Cost, Level Shifted Low Side Current Monitor for Negative High Voltage Rails

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tested for quick and easy system integration to help solve today’s
analog, mixed-signal, and RF design challenges. For more
information and/or support, visit www.analog.com/CN0188.
Circuit Note
CN-0188
Devices Connected/Referenced
ADA4051-2
Micropower, Zero-Drift, Rail-to-Rail Input
and Output, Dual Op Amp
AD7171
Low Power, 16-Bit, Sigma-Delta ADC
ADR381
2.5 V, Low Noise, High Accuracy, Band
Gap Voltage Reference
ADuM5402
Quad-Channel Isolator with
Integrated DC-to-DC Converter
Low Cost, Level Shifted Low Side Current Monitor for Negative High Voltage Rails
EVALUATION AND DESIGN SUPPORT
Circuit Evaluation Boards
CN-0188 Circuit Evaluation Board (EVAL-CN0188-SDPZ)
System Demonstration Platform (EVAL-SDP-CB1Z)
Design and Integration Files
Schematics, Layout Files, Bill of Materials
CIRCUIT FUNCTION AND BENEFITS
The circuit shown in Figure 1 monitors current in individual
channels of −48 V to better than 1% accuracy. The load current
passes through a shunt resistor, which is external to the circuit.
The shunt resistor value is chosen so that the shunt voltage is
approximately 50 mV at maximum load current.
R1
24.9k
0.1µF
D1
5.6V
R2
1k
1%
10µF
VIN
ADR381 ^VOUT
GND
GND_ISO
R7
4.99k
1%
+3.3V_ISO
+2.5V
0.1µF
REFIN(+) VDD
AIN+
SCLK
AD7171 _PDRST
AIN
REFIN(–) GND ^DOUT
V_ISO
V_DD1
ADuM5402
V_OA
V_IA
V_OB
V_IB
V_IC
V_OC
+3.3V
U1:
ADA4051-2
U1A
U1B
R6
1k
Q1
R3
48.7k , 1%
R4
R5
1k
4.99k
1%
1%
GND_ISO
D2
GND_ISO
GND₁
GND_ISO
GND1
NOTE: OPTIONAL ADuM5402 PROVIDES
GALVANIC ISOLATION FOR DIGITAL SIGNALS
AND ISOLATED POWER FOR CIRCUIT
D1: MMSZ5232B-7-F
D2: MBRA120ET3
Q1: ZXMN7A11GTA, 70V N-CH MOSFET
48V
SOURCE
+
R_SHUNT
–
+
V_SHUNT
I_LOAD
LOAD
GND_ISO
Figure 1. Low Side Current Monitor for Negative High Voltage Rails (All Connections and Decoupling Not Shown)
Rev. B
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